Lead singer of the popular band Nittle Grasper along with Tohma Seguchi and Noriko Ukai, and friend of Shuichi. He left the band three years ago to pursue a solo career in America but returned to Japan to reform Nittle Grasper. Shuichi is excited at the news of Nittle Grasper's reunion, but that now makes Ryuichi his rival. Ryuichi is kind and sometimes seems to have the mind of a five-year-old, until he starts singing; then he becomes a really cool, mature, vocal god. Other characters have noticed that Ryuichi and Shuichi are quite similar in their child-like manner. His best friend is a pink bunny named Kumagoro (Mr. Bear in the English version), which is from K-san, his old manager. It contains a tracking device, and is from the K brand stuffed animal line. Not much is known about his past.
The author, Maki Murakami, supposedly named Ryuichi Sakuma after famous Japanese music composer and actor "Ryuichi Sakamoto."
One of Ryuichi's defining features is his personality. For the most part he goes about life in a childlike state, hyper actively and naively. To further define this attitude, he carries around a stuffed pink rabbit named Kumagoro that he regularly talks to as though it were a living person and often plays with it in public. Though this sort of personality charms a lot of people, it also works for a lack of communication when other characters want to talk to him seriously.
There are few instances Ryuichi acts his age, most commonly when he's performing onstage. He'll drop the childlike demeanor and perform seriously. His serious side also emerges whenever he becomes upset or angry enough, which ends up scaring those who know his childlike side more. This side seems to emerge when he wants to make a point, though he acts more like a child when he wants to encourage someone or comfort them.
It has also been debated that Ryuichi shares in the homosexual plot. In the EX version of the manga, he is seen kissing Shuichi, making Eiri highly jealous. Most fans argue that this is only part of Ryuichi's childlike demure or that he's doing it to somehow bring Shuichi and Yuki closer together- perhaps to make Yuki appreciate Shuichi more.
Yet, fans who encourage this act say Ryuichi, does in fact, love Shuichi. In Gravitation there are clues that show how attached he is to Shuichi. In volume 12 of Gravitation he tells Tohma that he loves Shuichi, but he says it in a friendly way. In Gravitation EX, he got serious when his ringtone started playing and therefore acted infatuated with Shuichi. Ryuichi's character changes with his own or Shuichi's music. If he was acting like a child when he kissed Shuichi, it would have been obvious that he was scheming.
However, as the Gravitation Ex storyline moves on, we discover that Ryuichi's kissing Shuichi was recorded by Rage(Reiji) for her movie(which we see the ending scene and credits of, at the beginning of a later track). Therefore, it is somewhat safe to say that all bets are off--Ryuichi's serious side could have been simply acting to fill the dramatic part of causing Shuichi to cheat on Yuki. It could just as easily have been the serious side acting, but using the scene to live out his own desires or obsession with Shuichi. It is quite the complicated matter, as in Track 77 of Gravitation Ex, we also see that Ryuichi has two very distinct (almost akin to DID/MPD, perhaps) personalities, and that he acts differently when the more childish of those personalities has been 'dismissed' from his body by the more serious one.
In recent chapters, Ryuichi's serious personality has proclaimed that Shuichi was his and that obstacles like Eiri would be eliminated. On the other hand, Ryuichi's childish side claims that he just wants Shuichi's voice, so there is a debate going on between the two sides but there is no doubt that Ryuichi's serious side does lust after Shuichi.
Vocalist for the legendary band, Nittle Grasper which broke up for three years. Shuichi admires Nittle Grasper and in the manga admitted that he wanted to be like keyboardist Tohma Seguchi, and was a fan of Ryuichi. After the break-up, Ryuichi went over-seas to America to pursue a solo career and would do so until there was a revival of Grasper. He is bad at Japanese (especially vague characters), English is his strong point.
Ryuichi is based on Hiroyuki Takami of Access. This would make Tohma Seguchi based on Daisuke Asakura, which would make Tohma and Ryuichi access.